Vacuum-pump.



l LANGMUIR.

VACUUM PUMP.

APPLICATION 'FILED AUG-24. |916.

Patented Nov. 4, 19195.

Fig( Z. y

Inventor Irving Langmuir,

His JTttorneg.

"AssIGNon 'ro GENERAL E Lncrmc comm, A CORPORATION ORNEW Yoan,

' l, VACUILPUMP;

To all whom may concern: l

Be itknown that I, IRvING LANGMUIR,

citizen ofthe United States, residing at Schenectady, in the county of Schenectady, State of'New York','have 'invented -certain new and useful Improvements in lVacuum-- Pumps, of which the following Ais a' specication.

My present invention relates'to pumps for obtaining high vacua in inc losed receptacles such as bulbs for incandescent lamps, vapor rectifiers, X-rayv tubes, 'electron dischargel devices, etc., of the typedescribed and claimed in my prior application, Serial No.- 76,054, filed February 3, 1916.

The object of my invention is to provide improved forms of pumps of the type def 1 scribed in m prior application'whereby the operation o such apparatus Iwill be ren dered more efficient.' Affurther object of my' invention 'ijs' to simplify the 'construction of an apparatus othis nature. f n

Which I Theifeat'ures of' my' invention v consider novel are pointed out'withparticulanity inthe appended claims; 'the inven'- tiontself,-howevenboth as to its organization and what `I Consider itsprobable method of operation 'willibest be understood by referenceV tothe following description taken in connection@ withthe accompanyingI drawing' in which Figures "land 2 jshow partly in elevation and 'partly in section vtwo modifica'- tions of my deidad-Fig, 3'shows a cross- Vsa . exhausted. and. Fig.' 5 is a' cross `view o n-thelinel-4 of Fig. 1. y They pump indicated inlFig 1 comprises 40 sectional View and-Fig. 4 a longitudinal seetion offa modified form 'ofconduit connecting my devicewith' the vesselwhich is t6 be sectionalaleylindrical'metal vessel lcontracted at the top toform a mouth 2',v Withinthis vessel' is located a tubular vmember-orconduit which is' ared outwardly at the' bottom so as tosnugly f t the interiorwall of the vessel 1. A cylindrical ,cap4 is suspended by means ofv the 1 supports '4% from. the mouth ot' the vessel lfover' the upper end ofthe -`conduit 3. #The lowerv 'partof the "vessel 1 contains mercury anda' heating coil 6 pro- Vvided with terminals may be' utilizedtx)- jannu IRVING LANGMUIR, orf sen nlvnrrrrlmy,l NEW-Yonx,

l specieation of Letters recent.' Patented N ov. 4, 1919. y Appnc'atidn le'd August 24,1916. -segial No. 116,624. I I' vaporize the mercury and produce' a blast' i rected downwardlyby the cap 4 through- A the annular space 8 between the'tube 3 and the cap 4. lA member 9'which is tted by a `gas-tight joint to the neck' 2 .of the vessel. 1

rnishes a connection between the device and the neck lO'ofithe vessel which isto be exhausted. The mercury vapor when it emerges from the annular space 8 .into the ar condensingchamber' surrounding conduit 3 tends to How outwardly and strike' the wall-'fof the vessel 1, which wall maybe kept cooled -by means'of water circulating" into' the coiled pipe 11,'surroundingthe wallvof thevessel -1 as indicated,- and soldered thereto 'to provide a' gdod heat conduc tlve contact. The gas or vapor from the V'vessel 10 will pass throughthe annular con! duit 12 which surrounds the cap 4, come -in contactwith the stream of mercury vapor at the lower end 'of that conduit, andl be 'driven toward the lowerpart ofthe conden'singchamber.- It maybe removed from the lower part of the condensing chamber bymeans of '-a pump 'connected thereto through tube 13.V The mercuryvapor will strikethecooled wall of vessel L and'be con:

- densed and thus be prevented from flowing. toward the vessel which is being exhausted. All of the condensed mercury will fall` tothe bottom ofthe. vessel land willbe 'returned 'I through the 'openings -14 in the bottom of`- '/the .tubular member-3 to the main body of. mercury.v A baille 15`which .is in good-con- L; f

tact with the -wall ofthe vessel 1, but which makes1'. imperfect' contact with the tubular membe'rf 3 is provided as shown' .in order v90.

thatl the-falling mercury will not. strike the heatedsurface at 16 of--t'heutubu'lar member v and be rev'aporated, -flhisbaiiie will -keep aromathe-pephery'pf this" bane. Win n, 95

low the-` Ine'rcuryto flow down through the and be supported/by'. aA metallic base 2Q from which the parts which are heated may be separated by heat insulation members 21.' It will be noted that with the construction herein shown the mercury which may be condensed upon the wall of the vessel 1 will fall to the bottom thereof away from the point where the passages 8 and 12 join. In the form ofpump shown in my prior application the stream of mercury vapor is directed upwardly and part or' the mercury which is condensed falls and is collected in a groove around the heated central conduit and at a point between where the two passages join and the vessel which is being exhausted. wWith this construction it is possible for some of the mercury to reevaporate and flow toward the vessel which is being exhausted in opposition to the gas which is being removed. By the construction which I have described above this diiculty is over-- come.

The form of my invention shown in Fig. 2 is similar in its operation to that shown in Fig. 1. In this case a bulb 22, which may be of glass, contains the mercury and the mercury vapor which is produced therein by means of a heating element 28, passes through the curved tube 24 into the con (lensing chamber 25. The annular space 26 between this tube and the condensing chamber communicates with the conduit 27 which in turn is connected to the trap 28 while another conduit 29 furnishes communication between this trap and the vessel to be exhausted. The walls of the condensing chamber 25 may be kept cooled by means of water circulating in jacket 30 surrounding the condensing chamber. The condensed mercury falls to the bottom of the condensing chamber and is returned to the .bulb 22 through the tube 31. The conduit 32 communicates with any convenient form of exhaust pump which is capable of producing a vacuum somewhat lower than the vapor' pressure of mercury at the temperature at which the bulb 22 is maintained. The bulb 22 and tube 241 may be covered with asbestos or other heat insulating material 33.

In the operation of a device of this character there will be a slight flow of mercury vapor through the conduit 27 to the trap 28 at a pressure about two microns, that is, a pressure corresponding to the vapor pressure ot mercury at ordinary temperatures. By cooling the trap 28 with liquid air this vapor may be condensed therein. The gas which is being pumped out of the receptacle has to flow through conduit 27 in opposition to this stream of mercury vapor and the larger this conduit is made the greater will be the opposition offered by the mercury vapor to the flow of the stream of gas which is being removed. By sub-dividing the conduit through which the gas is removed, however, into a plurality of narrow passages, as, for example, by means of diaphragms 34, separated by spacing blocks 35, as indicated iii Figs. -3 and 4;, this difficulty may be overcome to a large extent since a large part of the pressure of the mercury vapor will be expended upon the walls of the passages instead of in opposing the flow of gas away frointhe receptacle.

While I have shown and described the preferred forms of my invention I do not wish to be limited to the particular forms described as it will be apparent that many modifications therein may be made without departing from the scope of my invention as set forth in the appended claims. I have described the operation of my pumps with mercury vapor as I find that this is especially suitable for operation at very low pressures. Its operation, however, does not depend upon the use of mercury as the necessary stream of vapor may be derived from other liquids.

What I claim as new and desire'to secure by Letters Patent of the United States, is

1. An apparatus for obtaining a high vacuum in a closed receptacle comprising means for producing a stream of vapor, said apparatus being arranged to form a condensing chamber, a conduit through which the stream of vapor may flow downwardly into the condensing chamber, a second conduit connecting with the receptacle which is to be exhausted and the condensing chamber and means for preventing vapor from [iowing through the second conduit toward the receptacle which is to Ibe exhausted.

2. An apparatus for exhausting closed receptacles comprising meansfor producing a stream of mercury vapor, said apparatus being arranged to orin a condensing chamber, a conduit through which the stream of mercury vapor flows downwardly into the condensing chamber, a second conduit coininunicating with the receptacle which is to be exhausted and with the condensing chamber, and means Jfor preventing mercury vapor. from flowing through t-he second conduit toward the receptacle which is` to be exhausted. I

3. An apparatus for exhausting closed receptacles comprising means for producing a stream of vapor, said apparatus being arranged to form a condensing chamber, a conduit through which the stream of vapor tlows downwardly into the condensing chamber, a second conduit communicating with the receptacle which is to be exhausted and the condensing chamber, and means for condensing the vapor near the point where the second conduit joins the condensing chamber.

4. An apparatus for exhausting closed receptacles comprising means for producing a stream of mercury vapor, said apparatus being arranged to .form a condensing chamber, a'conduit through ywhich the stream of mercury .vapor -ilows downwardly into,l the condensing. chamber, a second conduitcom-v V municating with the receptacle which is to .be exhausted and -with'the condensing"cha'rn- A.

ber, and means for condensing the mercury vapor nearthe point where the' second confrom iiowingfrom the condensing chamber duit connects with the .condensing chamberl' in such a way as to yprevent mercury vapor into the second conduit.;l j v 5.*An apparatus for removing gas o1"- va'- por-froml a receptacle comprising means for.

Eroducing a stream of vapor, said apparatus eing arranged to form a condensing cham-y ber, a conduit throughv'which a streamof mercury, a 'conduitlfthrough which the stream of mercury vapor thus produced is,

vapor flows downwardly into the condens ing chamber, a second conduit communicat-l ing. with thereceptacle.` from fwhich the gas or vapor is to be removed, and opening downwardly into the condensing chamber, and means for cooling the wall of the condensingchamfber near ,the point where it communicates lwith the secondlconduit.' I

6. An apparatus for exhausting closed re.

ceptacles comprising meansV for producing' aI stream of mercury vapor, said apparatusbeing larranged to form' a condensing chamber, a condult through which the stream of mercury vapor flows downwardlyl into the condensingichamber, a second conduit coms municating with the receptacle which is to be exhausted .and whichalso opens downwardly` into. the condensing chamber, and means :for preventing the mercury, vapor from iiowing through-the `second conduit toward the receptacle-` whichl is to -be ex" 'haus'ted '7, 4An apparatusfor exhausting closed r'e-I ceptacles comprising means for producing V'a stream-of mercury .vapor,'said apparatus being arrangedto form a condensing cham-- ber, a conduit through which the stream of mercury vapor flows downwardly into the condensing chamber, al1- -annular lconduit surrounding the yfirst conduit and providing? communication betweenv the receptacle which is to be'exhausted and the condensing cham.

b`er, and means for preventing mercury from owing through said' annular conduit into the vessel which is to' be exhausted.

8'. An apparatus 'for exhausting closed.- receptaclescomprising-a vessel adapted to i contain mercury, A means forv heating vthe lower part of-'said vessel to vaporize the f be :exhausted andthe condensing chamber, andmeans for cooling the wall of the condensing fchamber near. the point .where Lit communicates with` the second conduit receptacles comprising means for producing a stream of mercury vapor, said apparatus being arranged to form a condensing chamber, ayconduit through which the stream'of mercury vapor flows to the condensing f chamber, asec'ond condult commumcatmg with the receptacle to be lexhausted and the condensing chamber, means for preventing '9. An apparatus lforl exhausting closedl mercury vapor from owing through the second conduit toward the receptacle which 1s be exhausted and a conduit through whlch gas may beremoved from the convdensing chamber, fthe whole being so varcon ensing chamber will tend to move 'away from the conduit which communicates with the receptacle to be exhausted.` 'a

410.@An apparatus for exhausting close receptacles comprising means for producing `a stream'of vapor, said apparatus being ar? ranged 4te form'al condensing chamber, a

conduit through which'the stream of vapor flows to the condensing chamber, a second ranged that the mercury condensed'in the conduit lcommunicating with the receptacle to be :exhausted and the condensing chamber, means for preventingthe vapor from owing through the second conduit toward v the receptacle which is'to be exhausted and a" conduit through which gas may bet removed from the condensing chamber, the whole' being so .arranged that the vapor condensed in the* condensing chamber will tend to move away from the conduit whichv i i communicates-withi the-receptacle to beexwhich' gas may bearemoved.

11. An apparatus forexhaus'ting closed hausted and'toward the conduit through receptacles comprising means f cr Aproducing a. streamof mercury vapor, saidl apparatus.

being arranged to form a condensingchamdber, a conduit through which the streamy ofmercury vapor flows tothel condensing chamber, a second condult communlcatmg with the receptacle whichis to be exhausted and with the condensing chamber, merns for condensing.' the mercury.` vapor near'the point where the second conduit joins 'the' condensing chamber and av third conduit A a through which gas may bexremoved from the-condensing chamber, the whole being; I

vso arranged that'the condensed mercury will 'tend to move away 'from the second conduit and towardthe third conduit.

12. apparatus'forv exhausting closed receptacles comprising means for producing a stream of vapor, .sald apparatus being ar ranged to form a `condensing chamber; a conduit through which the stream of vapor flows to the condensing chamber, asecond conduit communicating with the receptacle which is to he exhausted :1nd with the condensing chamber, said second conduit throughout u portion of its length being sub-divided into a plurality of narrow passages und mea-ns for preventing` vapor from flowing' through the second conduit toward the vessel which is beingexhausted.

13. An apparatus comprising a conduit through which :t stream of vapor tends t0 flow in opposition to a stream of gas, said conduit being divided into a plurality of small passages in order to minimize the 0pposition offered by the vapor to the gas.

In Witness whereof, I have hereunto set 15 Witness BENJAMIN B. HULL. 

